The present invention in various embodiments relates generally to the useful manipulation of infrared components found in toners as commonly utilized in various printer and electrostatographic print environments. More particularly, the teachings provided herein relate to at least one realization of infrared encoding of data elements or infrared marks.
It is desirable to have a way to provide for the detection of counterfeiting, illegal alteration, and/or copying of a document, most desirably in a manner that will provide document security and which is also applicable for digitally generated documents. It is desirable that such a solution also have minimum impact on system overhead requirements as well as minimal storage requirements in a digital processing and printing environment. Additionally, it is particularly desirable that this solution be obtained without physical modification to the printing device and without the need for costly special materials and media.
Watermarking is a common way to ensure security in digital documents. Many watermarking approaches exist with different trade-offs in cost, fragility, robustness, etc. One prior art approach is to use special ink rendering where the inks are invisible under standard illumination. These inks normally respond light outside the visible range and thereby may be made visible. Examples of such extra-spectral techniques are UV (ultra-violet) and IR (infrared). This traditional approach, is to render the encoded data with special inks that are not visible under normal light, but have strong distinguishing characteristics under the special spectral illumination. Determination of the presence or absence of such encoding may be thereby subsequently performed using an appropriate light source and detector. One example of this approach is found in U.S. Patent Application No. 2007/0017990 to Katsurabayashi et al., which is herein incorporated by reference in its entirety for its teachings. However, these special inks and materials are often difficult to incorporate into standard electro-photographic or other non-impact printing systems like solid ink printers, either due to cost, availability or physical/chemical properties. This in turn discourages their use in variable data printing arrangements, such as for redeemable coupons or other personalized printed media for example.
Another approach taken, is a document where copy control is provided by digital watermarking, as for example U.S. Pat. No. 5,734,752 to Knox, where there is provided a method for generating data encoding in the form of a watermark in a digitally reproducible document which are substantially invisible when viewed including the steps of: (1) producing a first stochastic screen pattern suitable for reproducing a gray image on a document; (2) deriving at least one stochastic screen description that is related to said first pattern; (3) producing a document containing the first stochastic screen; (4) producing a second document containing one or more of the stochastic screens in combination, whereby upon placing the first and second document in superposition relationship to allow viewing of both documents together, correlation between the first stochastic pattern on each document occurs everywhere within the documents where the first screen is used, and correlation does not occur where the area where the derived stochastic screens occur and the image placed therein using the derived stochastic screens becomes visible.
With each of the above patents and citations, the disclosures therein are totally incorporated by reference herein in their entirety for their teachings.
Disclosed in embodiments herein, is an infrared mark or data encoding where the difference in visible response to infrared response is based on the metameric character of standard non-impact printing materials.
Further disclosed in embodiments herein, is a system for creating an infrared mark comprising two distinct colorant combinations that under normal illumination yield an identical or similar visual tristimulus response, but under infrared illumination can easily be distinguished using standard infrared sensing devices such as cameras.
Further disclosed in embodiments herein, is a system for creating an infrared mark employing the different infrared transmission characteristic of standard non-impact printing materials, specifically the different infrared transmission characteristics of the four or more printing colorants, whereby the application of such infrared transparent colorants on a substrate results in a high level of infrared reflectance of the combination due to the substrate reflectance characteristics. The infrared mark is created by printing the first colorant combination with a relatively high infrared reflectance in direct spatial proximity to a second colorant combination having the essentially same visual response under visible light, while having a different infrared reflectance by changing the relative amounts of the colorants in the mixture in a manner that is essentially invisible to the human eye under normal illumination.
Further disclosed in embodiments herein, is an infrared mark indicator comprising standard digital printing material (toner, ink, dye and the like) where the individual components (e.g.: 4 toners and one substrate) have at least in part differentiable IR characteristics, a first colorant mixture and a second colorant mixture printed as an image upon the substrate. The first colorant mixture when applied to a common substrate having a high infrared reflectance. The second colorant mixture is printed as an image upon the substrate in substantially close spatial proximity to the printed first colorant mixture. The second spatial color pattern having a low infrared reflectance when applied to a common substrate, and a property of low contrast against the first spatial color pattern under normal illumination. The arrangement is such that the resultant printed substrate image suitably exposed to visible light will have no obvious contrast or distinction between the two colorant mixture and under infrared illumination, will yield a discernable pattern evident as an infrared mark, by exhibiting discernible first and second levels of infrared reflection, made visible by a standard infrared sensitive sensing device, such as an infrared camera.
Further disclosed in embodiments herein, is an infrared mark indicator comprising an infrared reflecting substrate and a first colorant mixture printed as an image upon the substrate. The infrared mark indicator further comprises a second colorant mixture printed as an image upon the substrate in substantially close spatial proximity to the printed first colorant mixture. The resultant second colorant mixture has the property of high infrared reflectance in conjunction with the substrate, and a property of low visual contrast against the first colorant mixture, such that the resultant printed substrate image suitably exposed to an infrared illuminant, will yield a discernable pattern evident as a infrared mark when viewed with an infrared sensing device.
Further disclosed in embodiments herein, is a system for creating an infrared mark comprising an infrared reflective paper substrate and a digital color printing system. The digital color printing system further comprises at least one first colorant mixture printed as an image upon the substrate having a property of high infrared reflectance in connection with the substrate. The system also includes at least one second colorant mixture printed as an image upon the substrate in substantially close spatial proximity to the printed first colorant mixture, the resultant second colorant mixture having a property of low infrared reflectance in connection with the substrate and a property of low visual contrast against the first colorant mixture. The system further includes an image printed with the digital color printing system on the paper substrate, the image comprising at least said first colorant mixture and said second colorant mixture arranged in close spatial proximity to each other, the spatial image arrangement of the at least two colorant mixtures revealing an infrared mark to a suitable infrared sensitive device when the printed color image is exposed to infrared illumination.
Further disclosed in embodiments herein, is an infrared mark indicator comprising an infrared reflecting substrate and a first colorant mixture printed as an image upon the substrate, the first colorant mixture having a property of high infrared reflectance in conjunction with the substrate. The infrared mark indicator further comprises a second colorant mixture printed as an image upon the substrate in substantially close spatial proximity to the printed first colorant mixture, the second colorant mixture having a property of low infrared reflectance in conjunction with the substrate, and a property of low visual contrast against the first colorant mixture, such that the resultant printed substrate image suitably exposed to an infrared illuminant, will yield a discernable pattern evident as a infrared mark when viewed with an infrared sensing device.